Art of impregnating timber and other material with a preservative.



UNITE sra'r s OLIVER P. M GOSS, OF SEATTLE, WASHINGTGN.

ART OF IMPREGNATING TIMBER AND OTHER MATERIAL WITH A PBESERVATIVE.

No Drawing.

To all whom it. may concern:

Be it known. that I, ()Iavnn I. M. (loss, av citizen of the UnitedStates, and a resident of Seattle, county of King, State of Washington,have invented a certain new and useful Improvement in the Art of Impregenating Timber and other Material \Vith a Preservative, of which thefollowing isv a specification.

My present invention is particularly concerned with the treatment oftimber, such as railroad ties, paving blocks, woodstave pipes, specialkinds of lumber, and the like, and it has for its special object theproducing'of ties which conform with the demands of the market at thepresent time, that is, ties which have been efiieiently, but notwastefully, impregnated with the preserving material, 'and furthermoreare thoroughly surface dry.

In order to f lly attain my object I preferably pursue the followingmethod: I place the timber to be, treated in a retort made with a dooradapted to be hermetically sealed. Then I introduce a preservative suchas coal tar, creosote, or other b-ituminous liquids into the retort,after which 1 heat the preservative to a temperature of approximately230 degrees Fahrenheit under normal pressure; then I draw a vacuum offrom 15 to 28 inches-in the retort; then, without disturbing such vacuumin the retort, I maintain the. 'heat of the latter at a temperatureabove that of boiling water under such vacuum, for not less thanone-half hour. Then I break the vacuum -the retort, and then. applypressure on thefluid in the retort suflicient to force into the ores ofeach cubic foot of the material eing treated approximately from 5 to 20pounds of the fluid. r

In order to render the surface of the treated material dry, thefollowing additional steps must be taken. Reheat the fluid in the retortfrom 1 to 6 hours additional to the temperature of from 200 to 240degrees I ahrenheit, then empty the retort of the preserving fluid; and,finally, while the material is still in the retort, and hot, draw thevacuum in the latter offrom 15 to 28 inches. By this process the surpluspreservative will be drawn out ofthe poresot the material and the latterthus renders the surface dry. The reheating ot the preservative willcause the gasesin the pores to J expand and thus facilitate therejection of Specification of Letters Patent.

Application filed October 11, 1915. Serial No. 55,2i77.

the surplus preservative when the final vacuum is drawn. i i hen thematerial is finally taken from then-tort and cooled, the contraction ofthe gases in the pores will tend to draw the remaining preservative wellinto the 'pores and thus leave the surface of the material dry. I l

The above described process will not he su-fi'icient to insure thethorough penetration of the preser'ative into the pores of somematerial. -In this case the following procedure should be substitutedfor the steps outlined in theforegoing paragraph. Reheat the fluidinsthe retort for from 1 to 6 hours, continuously, to a temperature oifrom 15. to 28 inches on the preserving fluid in the retort, then, whilestill under suco vacuum, continue the heat above the boiling point ofwater under the vacuum for not less than one-half hour, then break said1 vacuum and empty the retort of the preserving fluid; and, finally,while the material is still in the retort, and hot, draw a vacuum in thelatter of from 15 to 28 inches up roximately.

I n describing my process I have necessarily to avail myself of a widerange in the degree of heat, in the vacuum produced, and in the lengthor time during which a specifio treatment is carried on, for it isimpossible to be more specific in these details,

since different materials have difi'erent na tures and requirecorresponding variation of their treatment. These specific details must,in the first instance, be determined for the different materials by apreliminary trial.

In short, the variations of my process are for the purpose or limitingthe Work done on the material to that required, in order to attain thebest results, in which the following is essential: First, the thoroughexpulsion of moisture from the timber, second.

the foreingof sufii'cient preservative ivcll into the pores of thematerial, and lastly. the e]ect10n of surplus preservative so that thesurface' of the treated material will he dry, which conditions aregenerally demanded by the market.

pressure, then drawing a vacu'um'e'l' a p proximately 15 to 28 inches inthe container and maintaining the heat of the latter at a temperatureabove that of boiling water under said vacuum for not less tli nhalf anhour,

then breaking such vacuum, and applying" under said 'vacumn, for notless thanhalt an hour, then breaking such vacuum, and applying pressuresulllclent to force approximately from 5 to Zn pounds of thepreservative fluid into the pores of each. cubicfoot of material, thenreheating the fluid .in th e container for from. one to six hourscontinuously to a temperature of from 200 td2l0 degrees .ll ahrenheitunder normal pressure, then emptying the container of the preservingfiu1d,.and

QinatelyQ then, while the material is v f still hot, drawing a vacuum inthe container of from 15 to 2b inches approxnnately.

3. In the preserving treatment of porousmaterial, the method whichconsists in first heating the; material in a 'hitulnlllolls'preservative", in a? closed container, to approximately 230 degreesFahrenheit under 1101' mat pressure, then drawing a vacuum ofapproximately 15 to 28 inches on the preserving lluid and continuing toheat the latter to a temperature above that of boiling water under saidvaclnlnntm' not less than halt an hour, then breaking such vacuum, "andapplying pressure sutliciehtly to force approximately from 5 to 2()pounds of the pr-eservat'ire fluid' 'into the pores of each cuhic teotof material, then reheating; the

fluid in the centainerfor fI'OIIY'OIlG to six hours continuously to 'atemperature of from 200 to 2&0 degrees Fahrenheit under normal pressure,thenilrawingga vactjuini of 15 to 28 inches on 'preservingfluid andboiling in the fluid under; this yacuu'm for not less than one hour,tlienj breaking such acuum and en jtj ingtlie cOntainer of the,preserving' flu d, and=t"hen,While the material is still' hot, drawing'a vacuum in the

